Measurement of Micro Kinetics of Hydrogenation in Liquid Phase Using Raman Spectroscopy

Hydrogenation of liquid organic hydrogen carriers is usually carried out in liquid phase. To measure the kinetics of this hydrogenation, an experimental setup using in situ Raman spectroscopy for analysis of the reaction mixture is proposed. With this setup it is possible to perform hydrogenation reactions at temperatures of up to 573 K and pressures up to 25 MPa. For validation of the experimental setup the hydrogenation of 1‐octene was measured in liquid phase. The reaction progress can be monitored in detail by Raman spectroscopy. To determine kinetic parameters from the experimental data, two modeling approaches were applied: a classic kinetic model and a thermodynamic kinetic model. The results were compared to literature data.     

Process and performance optimization by selective assembly of battery electrodes

The increasing demand for electric vehicles and thus lithium-ion batteries results in a multitude of challenges in production technology. The reproducibility and performance of large scale batteries for automotive applications are very high. At the same time the production processes are complex and involve many uncertainties. Two essential process steps are the electrode coating and electrode package assembly. The mass loading of anodes and cathodes are determined by the coating process, where deviations can be caused by different reasons. The selective assembly of the electrodes is a reasonable way to balance the production variances. The contribution shows extended algorithms and their benefits and drawbacks of matching electrodes in order to improve the subsequent electrode packaging process. Here, the aim is to reach higher cell capacities and optimized performance values by “optimally” balanced electrodes regarding the mass loading ratio, which is also related to the specific material capacity.     

Gallium gradients in Cu(In,Ga)Se2 thin‐film solar cells

The gallium gradient in Cu(In,Ga)Se₂ (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe₂ and CuGaSe₂ were calculated using density functional theory. The migration barrier for the In_Cu antisite in CuGaSe₂ is significantly lower compared with the Ga_Cu antisite in CuInSe₂, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd.     

Partial oxidation of methane in hollow‐fiber membrane reactors based on alkaline‐earth metal‐free CO2‐tolerant oxide

The U‐shaped alkaline‐earth metal‐free CO₂‐stable oxide hollow‐fiber membranes based on (Pr_0.9La_0.1)₂(Ni_0.74Cu_0.21Ga_0.05)O_4+δ (PLNCG) are prepared by a phase‐inversion spinning process and applied successfully in the partial oxidation of methane (POM) to syngas. The effects of temperature, CH₄ concentration and flow rate of the feed air on CH₄ conversion, CO selectivity, H₂/CO ratio, and oxygen permeation flux through the PLNCG hollow‐fiber membrane are investigated in detail. The oxygen permeation flux arrives at approximately 10.5 mL/min cm² and the CO selectivity is higher than 99.5% with a CH₄ conversion of 97.0% and a H₂/CO ratio of 1.8 during 140 h steady operation. The spent hollow‐fiber membrane still maintains a dense microstructure and the Ruddlesden‐Popper K₂NiF₄‐type structure, which indicates that the U‐shaped alkaline‐earth metal‐free CO₂‐tolerant PLNCG hollow‐fiber membrane reactor can be steadily operated for POM to syngas with good performance. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3587–3595, 2014     

Photo-vulcanization using thiol-ene chemistry: Film formation,morphology and network characteristics of UV crosslinked rubber latices

The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.     

优化车门ECU功耗的新概念

<正>在现代汽车中,电子控制单元(ECU)的数量不断增长。现代电子零部件增加了许多功能可为驾驶员提供更多的信息和更舒适的环境,